Source : Webster's Revised Unabridged Dictionary (1913)

Orchotomy \Or*chot"o*my\, n. [Gr. ? a testicle + ? to cut.]
   (Surg.)
   The operation of cutting out or removing a testicle by the
   knife; castration.

Source : WordNet®

orchotomy
     n : surgical incision into the testis to obtain material for
         analysis (as in cases of abnormally low sperm count)